Electrical time-switch



L. H. I. T. BIZI'IIIISEII.

ELECTRICAL TIME SWITCH.

, APPLICATION FILED Aue.29, 1917.

1,3353%. Patentad Mar. 30,1920.

- Q I I 4 s H 8 79 LAUBI'IZ HARALD JOHAN THEQDOR BJfiRNSEN, OFCOPENHAGEN, DENMARK.

ELECTRICAL TIME-SWITCH. I

Specification of Letters Patent. Patented ltlar. 30, 1920.

Application filed August 29, 1917. Serial No. 188,846.

To all whom it may concern:

Be it known that I, LAURITZ HARALD JOHAN Tnnooon BJoRNsnN, subject ofthe King of Denmark, residing at Copenhagen,

Denmark, have invented certain new and useful Improvements in ElectricalTime- Switches, of which the following is a specification.

The present invention consists of an electrical time switch of the kindwhere the heat produced by an electrical current causes a body toexpand, the said expansion and subsequent contraction being utilized toclose or interrupt an electrical circuit. I

r The essential feature of the invention is a heat-operated memberclosing, by means of the heat produced by the operating current, thecircuit for another heat-operated member which thereby closes the maincircuit. i

On the drawing is shown, in diagram, one manner of. constructing theinvention as utilized for a so-called staircase automaton.

1 and 2 are the feeding wires, positive and negative respectively, 3 thelamps, 4 the push-button switches and L, M, P, T the connectingterminals. 5 and 6 are-two metal bars firmly interconnected at bothends, one of'the bars facing anincandescent lamp 7 so that the latterwhen burning heats the bar 5 which, by the elongation produced thereby,moves a contact 8 toward an adjusting screw 9.

15, 16, 17 18 and 19 are a contact system corresponding to 5, 6, 7, 8,9. p

The apparatus acts in the following manner:

By the depression of oneof the push-.

buttons 4, a clrcuit is closed from the positive terminal P and throughthe switch 4, the terminal T and the incandescent lamp 17 to thenegative terminal M.- The heat radiating from the lamp will heat themetal bar 15 and thereby, within a short time, it will bring the contactpiece 18 into contact with the screw 19. By this contact, a new circuitis closed from the positive terminal P and through the contacts 18,-19and the "incandescent lamp 7 to the negative termi- 'nal M. The heatradiating from the incandescent lamp 7 will soon bring the contact piece8 into contact with the contact screw whereby a new circu t-the maincircuitis closed from the terminal P throu h the insu lamps 3, theconnecting terminal the whereby the circuit between the incandescentlamp 7 is broken, and the bar 5 begins to cool down. When the coolinghas progressed so far that the contact 8 is brought out of contact withthe contact-screw 9, the main current is interrupted and the lamps 3 areextinguished.

Ex eriments have shown that it is practicab e to reduce to about onesecond the time during which it is necessary to depress a push-button inorder to cause the lamps 3 to burn and, further, that by adjusting thescrews 9 and 19 the length of time during which the lamps continue toburn may be varied between 1 and 5 minutes or, if desired, between stillwider limits.

Ordinarily, the pressure on the push-but-v ton 4 will be released assoon as the lamps 3 begin to burn. If it besdesired, however, to havethe lamps burning somewhat beyond the normal period, it is onlynecessary to keep the button depressed for a short time for instance onesecond-after the lamps have been lighted. Besides, it is feasible, atany time durin a burning period, to initiate a new period y depressing apush-button once more.

If oneof the push-buttons happens to be sticking in the circuit-closingposition, no other harm is roduced than that all the lamps 3, 7 and 1%continue to burn.

When the metalbars 5 and 6 as well as the bars 15 and 16 are made of oneand the same metal, the result is attained that the the apparatus havingbecome heated by having been used several times at short intervals. Ifnecessary, the bars 6 and 16 may beinsulated against heat action, forinstance by bein wound by or .inclosed in some heat fitting substance,or by being made narrower than the bars 5 and 15, so that the latterprotect them against the radiating heat.

A slower. cooling of the bars 5 and 15, if desired, may be attained binsulating them on the side m? facing the i amps.

Instead of the heat-operated devices 5, 6

' and 15, 16 there may be used heat-operated devices of any suitableconstruction, where a heating and subsequent cooling causes a circuit tobe closed and broken, respectively.

The apparatus described is free of the relatively expensive andunreliable clockworks and also of electro-magnets, and .it fills all therequirements to be made to a time switch, in respect to simplicity ofcon-v struction cheapness and reliability of performance. p

The main condition for attaining the high efiiciency in such simpleapparatus is t e nearly instantaneous heating of the bars 15 and 5caused by the radiating heat from the incandescent lamps l7 and 7, .inconnection with the subsequent very slow cooling.

Having now particularly described and ascertainedthe nature of my saidinvention and in'what manner the same is "to be performed, I declarethat what I claim is In an electrical time switch, a circuit having anelectrical heat-emitting member a second circuit having a thermalexpansihle circuit-closing element "in operative relation to theaforesaid heat-emitting member of .the first circuit, said secondclrcuit having alsoan electrical heat-emitting member a main circuithaving a thermal expansible circuit-closing element in operativerelation to said heat-emitting member of said second circuit, and meansfor breaking said first circuit, whereby, after the main circuit isclosed, it may be broken, after the lapse of a time'interval, by thesuccessive automatic cooling of the said circuit closing elements andthe successive automatic breaking of their respective circuits.

In testimony whereof the foregoing specification is signed in thepresence of two witnesses. Y

, mumrz 11.4mm) Jon rranonoa BJGBNSBN.

Witnesses:

Jul-ms LDMANN, .Av Gm'nsme.

